Thales was a native of Miletus, in Asia Minor. He flourished in 585 BCE (the date of an eclipse he is reputed to have predicted). No fragments of his work have survived, only testimony. Aristotle attributes the following four views to Thales:
1. The earth rests on water. (De Caelo 294a28)
2. Water is the archÃÂª of all things. (Metaph. 983b18)
3. The magnet has a soul. (De Anima 405a19)
4. All things are full of gods. (De Anima 411a7)
This seems like a very bizarre collection of very strange views. What makes these views philosophically or scientifically interesting? We will begin with (1). It seems very likely that Thales was offering an hypothesis to explain a puzzling phenomenon: why are there earthquakes? If the earth floats on water, then we can understand what happens: the earth is rocked by the wave action of the water on which it floats like a boat or a log.
(At this point we are more interested in seeing that this is an attempt at explanation than in evaluating it.)
To understand (2) we need to examine its source. ArchÃÂª is Aristotle's word: it means beginning or source or principle (cf. "archaic," "archaeology," "architect"). Aristotle is here talking about what he called the material archÃÂª, which can be either the stuff from which something originated or the stuff of which it is composed. Thus, Thales thought (Aristotle tells us) that everything either originated in water (cosmogony) or is actually (now!) made of water (constituent analysis).
So what is the scientific or philosophical interest of Thales' ruminations about water? He is attempting to provide a theory which is:
1. General (it covers a whole range of similar cases, not just a single one).
2. Based on observation (although it transcends all...